In the novel Tarzan of the Apes Kerchak is the "king" of a tribal band of Mangani, a fictional species of Great Ape intermediate between real life chimpanzees and gorillas. In the beginning of the original novel, Kerchak leads his band against Tarzan's marooned father and kills him; the infant Tarzan is saved by a female Mangani named Kala, who rears the baby and protects him against Kerchak. When Tarzan reaches adulthood, he fights and kills Kerchak and succeeds him as king of the apes.
Burroughs's later Tarzan book Jungle Tales of Tarzan, which relates additional details of Tarzan's youth among the apes, is also set during the period of Kerchak's rule of the ape band. However, while the ape band is continually referenced as "the tribe of Kerchak," Kerchak himself does not appear in the book.
Kerchak's character in the Disney adaptation (1999) was changed substantially from his original role in the series. In this adaptation, Kerchak has no role in the slaying of Tarzan's father but is portrayed as an over-protective leader of the ape group as well as the mate to Tarzan's adoptive mother, Kala. Kerchak shuns Tarzan during his childhood and only allows him to stay with the gorillas because Kala refuses to abandon him. Prior to this, however, he is shown as warm and loving, playing with his son. But after Sabor kills his child, Kerchak turns cold and hateful. He disdains Tarzan but gradually begins to accept him in adulthood after Tarzan proves himself by killing the leopard Sabor (responsible for killing Tarzan's parents, as well as Kerchak and Kala's son) and saving the group from the hunter Clayton (who leads a posse of poachers hoping to capture the apes and selling them for profit).
At the climax, when Kerchak helps the ape group fight against the poachers, he witnesses Tarzan getting shot on the arm by Clayton. Angered at this, Kerchak goes to attack Clayton, but gets fatally shot on the chest, much to Tarzan's anger and to Clayton's delight. After the final battle between Tarzan and Clayton (which ends with Clayton inadvertently cutting down the vines he's holding which leads himself to hang to his death), Kerchak passes his leadership position to Tarzan before dying of his injury, signifying his ultimate acceptance of him as both adopted son and a worthy successor.
Following real life apes, Disney also made Kerchak a silverback gorilla; which is the name given to mature male gorillas because of the silver hair covering their backs. He was voiced by actor Lance Henriksen.
The film's Kerchak is essentially a combination of the novel's Kerchak and another of the novel's ape characters, Tublat. In Burroughs's original story Tublat was Kala's mate, a fairly passive figure resentful of his foster-son Tarzan. The Kerchak of the film is closer in personality to Tublat than to the original Kerchak. However, in the spin-off television series, The Legend of Tarzan, Tublat appeared with a personality much like the original Kerchak, being violent and seeking revenge on Kerchak through Tarzan (being his successor as leader of the gorillas), having been cast out many years ago after he challenged Kerchak for leadership and lost.
Kerchak also appears briefly in the video game Kingdom Hearts. With no speaking lines, Kerchak first appears when Tarzan pleads with him and Kala to help him aid Sora, Donald and Goofy (in ape language, which the trio do not understand). Kerchak initially does not trust the trio, and matters are made worse when Clayton almost kills Terk, for the timely intervention of Donald (on whom Terk later develops a crush). However, Kerchak later comes to accept the trio after they defeat Clayton and his Heartless companion, the Stealth Sneak, and allows them access to the world's Keyhole, which Sora seals, protecting the world from the Heartless permanently.
In the original film Kerchak dies after being shot by Clayton, whilst in Kingdom Hearts he survives the fight. It is unknown if he has passed his leadership position onto Tarzan like he does in the film.